In general, a light guide panel is a part for receiving light from a light source and emitting light in the form of surface light having uniform brightness, and constitutes a backlight unit (BLU) of a liquid crystal display (LCD).
Referring to FIGS. 1 and 2, when a light guide member 4 used in manufacture of the light guide panel, for example, a light guide plate or a light guide film made of plastic, glass or the like is carved to form a pattern 8 of scratches or dots on a surface of the light guide member by laser machining, the pattern 8 scatters/refracts/reflects light emitted from the light source 3, thereby allowing the light guide panel to emit illumination light in the form of surface light.
However, since the light guide panel manufactured by laser machining simply emits light from the light source in the form of surface light with the same color as the light emitted from the light source 3, the surface light becomes monotonous and is not aesthetically pleasing.
Recently, a light guide panel has developed to scatter/reflect light emitted from the light source 3 by printing a light-diffusing ink on the light guide member 4 and forming a pattern 8 of dots on the surface of the light guide member 4. However, such a light guide panel using the light-diffusing ink simply scatters/reflects light of the light source at a portion on which the light-diffusing ink is printed, with the same color and uniform brightness, whereby the light guide panel itself cannot output aesthetically pleasing light. Although the light-diffusing ink generally improves brightness, there is a limit in application of the light guide panel to various fields besides the backlight unit.
In other words, a conventional light guide panel and, more particularly, the light guide member 4 has been applied to a backlight unit that uniformly illuminates a substrate of a liquid crystal display, or that is placed behind an image sheet 2 having a certain image, for example, a photo or picture sheet for a billboard or decoration board and illuminates a certain portion of the image sheet 2 with the same color as the light emitted from the light source 3.
Accordingly, the present inventor has developed a light-diffusing ink composition and a light guide panel using the same, which can convert light from a light source into aesthetic and sensuous light, and a light guide panel including a light-diffusing ink image and outputting an optical pattern image.